JPH09325630A - Image heater and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image at high heat-efficiency, highly speedily, and highly reliably by providing a member, with hardness lower than that of a fixing film and that of a side plate, between the end of the fixing film in its longitudinal direction and the side plate holding the fixing film. SOLUTION: The cap 70 having a thickness of 2mm, as the protective member, so provided as to cover the end of the fixing film 710 in its longitudinal direction rotates together with the fixing film 710. Ni electroforming is used to obtain the fixing film 710, the cap 70 is made of a POM material, and the hardness of the cap 70 is set so as to be lower than the hardness of the fixing film 710 and the hardness of the side plate 750 serving as a restraining member which restrains the fixing film 710 from skewing. Thus, by using the member, as the cap 70, whose hardness is lower than the hardness of the fixing film 710 and the hardness of the side plate 750, damage the end of the fixing film 710 can be prevented especially even in the case that the device is made to high-speed and highly durable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating device for generating and heating an eddy current by utilizing electromagnetic induction, and an image forming apparatus such as an electrophotographic copying machine, a printer or a facsimile which is equipped with this image heating device as a fixing device. Regarding the device. That is, an unfixed toner image formed directly or indirectly on the surface of the recording material by using a toner made of a heat-meltable resin or the like by an appropriate image forming process means such as electrophotography, electrostatic recording, magnetic recording, etc. The present invention relates to an apparatus and the like for performing a heat fixing process as a permanently fixed image on a recording material surface.

[0002]

2. Description of the Related Art Conventionally, as an image heating device represented by a heat fixing device, a fixing device of a contact heating system such as a heat roller system and a film heating system has been widely used. An electric current is applied to the heating resistor to generate heat, and the toner image is heated via a roller or a film.

Therefore, there is a slight distance between the heat generating position and the toner even in the film heating type fixing device, and the efficiency of energy consumption is inevitably reduced accordingly.

Therefore, as disclosed in Japanese Patent Publication No. 5-9027, a heating device has been proposed in which eddy current is generated in the fixing roller by magnetic flux and heat is generated by Joule heat, and the generation of eddy current is utilized. Thus, the efficiency of energy consumption was improved by bringing the heat generation position closer to the toner.

Further, in order to further improve the thermal efficiency, a fixing device of the type has been proposed in which an eddy current is generated in the film itself or a conductive member in the vicinity of the film to generate heat and heat the film.

[0006]

However, a film-type fixing device using electromagnetic induction, for example,
Even if the speed of the apparatus is increased or the durability is increased, the longitudinal end portion of the film may be damaged due to the sliding contact between the end portion of the film and the side plate of the fixing device.

Therefore, an object of the present invention is to have high thermal efficiency,
Another object of the present invention is to provide an image heating apparatus capable of high speed and high durability, and an image forming apparatus provided with this image heating apparatus and capable of high-speed and highly reliable image formation.

[0008]

According to the first invention of the present application, the above object is contained in a rotating body, a pressing member forming a pressure contact portion with the rotating body, and the rotating body itself. Alternatively, in an image heating apparatus having a heat generating portion arranged so as to come into contact with the rotating body and heating the material to be heated by sandwiching it in the press contact portion, the longitudinal end portion of the rotating body and the This is achieved by providing a member having a hardness lower than that of the rotating body and the side plate between the side plate holding the rotating body.

According to the second invention of the present application,
The above-mentioned object has a rotating body, an exciting coil provided inside the rotating body, and a pressure member that forms a pressure contact portion with the rotating body, and generates a eddy current in the rotating body, thereby rotating the rotating body. In an image heating device that heats itself, it is achieved by providing a member having a hardness lower than that of the rotating body and the side plate between the longitudinal end portion of the rotating body and the side plate that holds the rotating body. .

Further, according to the third invention of the present application, in the above-mentioned first or second invention, the object has a lower hardness than the rotor and the side plate at the longitudinal end portion of the rotor. This is achieved by providing a cap.

According to the fourth invention of the present application,
In the first or second invention, the above object is achieved by providing a plate member having a lower hardness than the rotating body and the side plate on the side plate holding the rotating body.

Further, according to the fifth invention of the present application, the above-mentioned object is to form a thermosoftening colored powder image on a recording material, and to carry out the recording material carrying the powder image as described above. The present invention can be achieved by fixing the powder image as a permanent image on the recording material to form an image by passing the powder image through the image heating apparatus according to any one of the first to fourth inventions.

That is, in the first aspect of the present invention, since the rotating body and the member having a lower hardness than the side plate are provided between the longitudinal end of the rotating body and the side plate holding the rotating body. By gradually scraping the low-hardness member itself, damage to the end portion of the rotating body is prevented, and high speed and high durability are realized.

Further, in the second aspect of the present invention, since the rotor and the member having a lower hardness than the side plate are provided between the longitudinal end portion of the rotor and the side plate holding the rotor. By gradually scraping the low hardness member itself, damage to the end portion of the rotating body is prevented, and the image heating device in which the rotating body itself generates heat realizes high speed and high durability.

Further, according to the third invention of the present application, since a cap having a hardness lower than that of the rotor and the side plate is provided at the longitudinal end portion of the rotor of the first or second invention, If this cap is abutted against one end of the side plate, the rotating body is held and the structure is simplified.

Further, according to the fourth invention of the present application, a plate having a lower hardness than the rotating body and the side plate is provided on the side plate holding the rotating body of the first invention or the second invention. Since it is unnecessary to cover the rotating body with precision like a cap, cost reduction can be achieved.

In the fifth invention according to the present application, a thermosoftening colored powder image is formed on a recording material, and the recording material carrying the powder image is recorded on the recording material according to the first invention to the above invention. Fourth
The powder image is fixed as a permanent image on the recording material to form an image by passing through the image heating device according to any one of the inventions. Since a member having a lower hardness than the rotating body and the side plate is provided between the portion and the side plate holding the rotating body, the low hardness member itself may be gradually scraped even when the speed is increased. This prevents damage to the end of the rotating body and realizes high durability. Therefore, high-speed and stable image formation is performed for a long period of time.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. 1, 4 and 5. FIG.
FIG. 3 is a cross-sectional view of an image forming apparatus using the image heating apparatus of this embodiment as a fixing device. In FIG. 5, reference numeral 1 denotes a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image bearing member. The photosensitive drum 1 is rotationally driven in a clockwise direction indicated by an arrow A at a predetermined peripheral speed (process speed), and in the course of the rotation, the primary charger 2 uniformly charges the negative dark potential V _D.

Reference numeral 3 denotes a laser beam scanner, which is a laser beam modulated corresponding to a time-series electric digital image signal of target image information input from a host device (not shown) such as an image reading device, a word processor, and a computer. Is output, and the surface of the photosensitive drum 1, which has been negatively and uniformly charged by the primary charger 2 as described above, is scanned and exposed by the laser beam, so that the exposed portion has a smaller absolute potential value and becomes the bright potential V _L. The electrostatic latent image corresponding to the target image information is formed on the surface of the rotating photosensitive drum 1.

Next, the latent image is subjected to reversal development (laser exposure portion _VL) with the powder toner negatively charged by the developing device 4.
Toner is attached to) to visualize the image.

The developing device 4 is a developing sleeve 4 which is rotationally driven.
a, the outer peripheral surface of the developing sleeve is coated with a thin layer of toner having a negative charge to face the surface of the photosensitive drum 1, and the developing sleeve 4a has an absolute value of the absolute value.
By applying the developing bias voltage V _DC which is smaller than the dark potential V _{D and} larger than the bright potential V _L , the toner on the developing sleeve 4 a is transferred only to the portion of the photosensitive drum 1 having the bright potential V _L. Latent image is visualized (reversal development).

On the other hand, the recording material 15 as the material to be heated, which is stacked and set on the paper feed tray 14, is fed out one by one by the drive of the paper feed roller 13 and fed, and the feeding guide 12
a to the nip portion (transfer portion) m of the photosensitive drum 1 and the transfer roller 5 as a transfer member which is brought into contact with the photosensitive drum 1 and to which a transfer bias is applied, via the registration roller pair 10 and 11 and the transfer guides 8 and 9. The toner image on the surface of the photosensitive drum 1 is sequentially transferred onto the surface of the feeding transfer material 15 by being fed at an appropriate timing synchronized with the rotation of the photosensitive drum 1. The resistance value of the transfer roller 5 as a transfer member is 10
^{A value of} about ⁸ to 10 ⁹ Ω · cm is suitable.

The recording material 15 that has passed through the transfer portion is the photosensitive drum 1.
After being separated from the surface, it is introduced into the fixing device 7 by the conveyance guide 12b, the transfer toner image is fixed, and is output to the paper discharge tray 16 as an image formed product (print). The surface of the photosensitive drum 1 after separation of the recording material is cleaned by a cleaning device 6 to remove residual toner such as transfer residual toner on the surface of the photosensitive drum, and is repeatedly used for image formation.

Next, the fixing device which is the image heating device of the embodiment of the present invention will be described in detail. First, the configuration of the entire fixing device will be described. FIG. 4A is a sectional view of the fixing device according to the present invention. In the figure, 710 is a fixing film as a rotating body, and the fixing film 710 is rotated in the direction of arrow B, and is pressed by a film guide 716 to a pressure contact portion (hereinafter referred to as a nip portion) n and the film is conveyed. Stability is achieved.

The fixing film 710 is shown in FIG.
As shown in the sectional view of (B), an elastic layer 702 such as rubber is provided on a heat generating layer 701 formed of a conductive member, and a release layer 703 is formed to prevent offset. It is composed.

The heat generating layer 701 is preferably made of a ferromagnetic metal such as nickel, iron, ferromagnetic SUS, or nickel-cobalt alloy and having a thickness of 1 to 100 μm.

As the elastic layer 702, silicone rubber,
It is preferably made of a material having good heat resistance and heat conductivity such as fluororubber and fluorosilicone rubber and having a thickness of 10 to 500 μm.

The release layer 703 is made of fluororesin (PF).
A, PTFE, FEP, etc.), silicone resin, fluorosilicone rubber, fluororubber, silicone rubber, and other materials having good releasability and heat resistance and a thickness of 1 to 100 μm are preferable.

Therefore, by generating a eddy current in the heat generating layer 701 of the fixing film 710 by the high magnetic permeability core 717 and the coil 718 which are magnetic flux generating means supported by the film guide 716, the heat generating layer 701 generates heat. However, the toner T on the recording material 15 can be heated at the nip n.

That is, the high-permeability core 717 is made of a material such as ferrite or permalloy that is used for the core of a transformer, and more preferably ferrite having a low loss even at 100 kHz or more, and is wound around the core 717. A high-frequency current of 20 kHz to 500 kHz is applied to the coil 718 from an exciting circuit (not shown) to generate a magnetic flux, and the change in the magnetic flux causes the heat generating layer 701.
An eddy current is generated in the heat generating layer 701 and Joule heat based on the specific resistance of the heat generating layer 701 causes heat generation.

On the other hand, in the fixing film 710 configured as described above, a pressure roller 730 as a pressure member is arranged so as to be in pressure contact with the guide 716 via the film 710. 730 and fixing film 71
The recording material 15 on which the unfixed toner T as the material to be heated is placed is passed through the nip n formed by 0 to heat and fix.

That is, the fixing film 7 is formed as described above.
The heat generated in the heat generating layer 701 of No. 10 is transmitted to the nip n through the elastic layer 702 and the release layer 703.
The recording material 15 nipped and conveyed between the recording material 15 and the toner T on the recording material 15.
Since the toner T is melted in the nip n and passes through the nip n, the toner T is cooled and becomes a permanently fixed image, and fixing is performed.

However, when the film is used as described above, the edge of the film and the side plate of the fixing device may rub against each other and the edge of the film may be damaged.

Therefore, in this embodiment, the structure as shown in FIG. 1 is adopted. FIG. 1 is a cross-sectional view of a longitudinal end portion (end portion in a direction orthogonal to the moving direction of the fixing film) of the fixing device that best represents the features of this embodiment. In FIG. 1, reference numeral 70 denotes a cap as a protective member having a thickness of about 2 mm, which is provided so as to cover the longitudinal end portion of the fixing film 710, and is adapted to rotate together with the fixing film 710. In the present embodiment, Ni electroforming is used for the fixing film 710 and POM material is used for the cap 70, and the hardness of the cap 70 is a side plate that is a regulating member that regulates the deviation of the fixing film 710 and the fixing film. 750
The feature is that it is set to be lower than the hardness of. The cap 70 has a ring shape.

For example, the hardness measured by a Barcol hardness tester according to JIS Handbook Plastic (Japanese Standards Association) is HBI-A70 for Ni electroformed film,
The POM cap was HBI-A40.

As the cap 70, a phenol resin,
Polyimide resin, polyamide resin, polyamideimide resin, PEEK resin, PES resin, PPS resin, fluororesin (PFA, PTFE, FEP etc.), LCP
(Liquid crystal polymer) A resin having a thickness of 0.5 to 3 mm made of a material having good heat resistance, such as a resin or a mixed resin thereof, is preferable.

By using a member having a hardness lower than that of the fixing film 710 and the side plate 750 as the cap 70, the end portion of the fixing film 710 is not damaged even when the speed and durability of the apparatus are increased. It becomes possible to prevent it.

That is, without the cap, the film edge directly contacts the side plate 750. Therefore, when the speed and durability are to be increased, the film edge is deteriorated and damaged, and the desired performance is not obtained. Although not obtained, when a cap 70 having a hardness lower than that of the fixing film 710 and the side plate 750 is used for the end portion of the fixing film 710, the cap 70 itself is gradually scraped, so that the fixing film 71 is removed.
It is possible to prevent breakage of the 0 end portion and realize high speed and high durability.

In particular, the fixing film of this embodiment has a metal layer made of Ni electroforming, but since the cap is mainly scraped off, it is possible to prevent burrs from being generated at the ends of the fixing film. It is possible to prevent the film from being damaged.

Further, by using the cap 70, the fixing film 710 can be simply abutted against one end of the side plate 750 and held, and the structure can be simplified.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the longitudinal end cap 70 of the first embodiment is used.
And the plate-like member 71 having a hardness lower than that of the fixing film 710 is provided inside the side plate 750 (on the side where the film ends contact).

As the plate member 71, phenol resin,
Polyimide resin, polyamide resin, polyamideimide resin, PEEK resin, PES resin, PPS resin, fluororesin (PFA, PTFE, FEP etc.), LCP
It is preferable to use a material having a high heat resistance such as a (liquid crystal polymer) resin or a mixed resin thereof.

With this structure, it is possible to prevent the end portion of the fixing film 710 from being damaged. Table 1 shows the durability test result of the member 71 in the present embodiment, and the durability test result when the member is not used as a comparative example and when the member 72 having a hardness higher than that of the fixing film 710 is further used instead of the member 71. Indicates.

[0045]

[Table 1]

As can be seen from Table 1, no member and member 7
When 2 is used, the end portion of the film is damaged at 200,000 sheets and 250,000 sheets, respectively, but when the member 71 is used, it is the minimum required as the fixing device of the image forming apparatus. It is possible to use up to a durable number of 300,000 sheets without causing damage to the edge of the film.

Further, the member 71 does not need to be covered with the fixing film 710 as a cap, which is advantageous for cost reduction.

The same effect can be obtained by using the same member 71 as that used in this embodiment as the side plate 750.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The present embodiment has the same configuration as the first embodiment except that a cap 73 is used instead of the cap 70 in the first embodiment. As in the first embodiment, the cap 73 has a hardness softer than the hardness of the film and the side plate, and as shown in the figure, is designed so that the portion in contact with the side plate 750 is inclined. is there. That is, the cap 73 has a conical shape, and the diameter increases toward the side plate 750. By doing so, not only the end portion of the film is prevented from being damaged, but also the rotation torque can be reduced because the contact area between the cap 73 and the side plate 750 is small. Further, since the cap 73 is gradually scraped through the durability, the contact position between the side plate 750 and the cap 73 also moves. Therefore, since the contact portions of the side plates 750 are not the same, the deterioration of the side plates 750 can be reduced. Furthermore, the life of the device can be warned from the movement of the contact position due to abrasion.

In the above-described embodiment, the case where the present invention is applied to the fixing device as an image heating device that heats the fixing film itself by eddy current has been described, but the present invention is not limited to this. The fixing film is provided separately from the film, and the fixing film is brought into contact with a heat generating portion that also serves as a guide of the fixing film, and the heat of the heat generating portion that is caused to generate heat by an eddy current is transferred to the heated material through the fixing film. It is also applicable to a fixing device as an image heating device. Further, it is also applicable to a fixing device as an image heating device in which a heat resistant film is slid on a heating resistor such as a ceramic heater and a pressure roller is brought into pressure contact with the heat resistant film.

[0051]

As described above, the first embodiment according to the present application is described.
According to the invention, since a member having a lower hardness than the rotating body and the side plate is provided between the longitudinal end portion of the rotating body and the side plate that holds the rotating body, the low hardness member itself gradually increases. By scraping, damage to the end of the rotating body can be prevented, and high speed and high durability can be realized.

According to the second invention of the present application,
Since a member having a lower hardness than the rotating body and the side plate is provided between the longitudinal end portion of the rotating body and the side plate that holds the rotating body,
By gradually scraping the low-hardness member itself, it is possible to prevent damage to the end portion of the rotating body, and it is possible to realize high speed and high durability in the image heating device in which the rotating body itself generates heat.

According to the third aspect of the present invention,
Since the cap of lower hardness than the rotating body and the side plate is provided at the longitudinal end of the rotating body of the first invention or the second invention, the rotating body is held by abutting this cap on one end of one side of the side plate. Therefore, the configuration can be simplified.

Further, according to the fourth invention of the present application, a plate member having a lower hardness than the rotating body and the side plate is provided on the side plate holding the rotating body of the first invention or the second invention. Since it is provided, it is not necessary to cover the rotating body with accuracy like a cap, and the cost can be reduced.

According to the fifth invention of the present application,
A thermosoftening colored powder image is formed on a recording material, and the recording material carrying the powder image is passed through the image heating apparatus according to any one of the first invention to the fourth invention. An image is formed by fixing the powder image as a permanent image on the recording material, and the image heating device is arranged between the longitudinal end portion of the rotating body and a side plate holding the rotating body. Since a member having a hardness lower than that of the rotating body and the side plate is provided, even when the speed is increased, the low hardness member itself is gradually scraped to prevent damage to the end portion of the rotating body, thereby improving durability. Therefore, high-speed and stable image formation can be performed over a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view of a longitudinal end portion of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a longitudinal end portion of a fixing device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a longitudinal end portion of a fixing device according to a third exemplary embodiment of the present invention.

FIG. 4 is a sectional view of a fixing device and a fixing film as an image heating device according to an embodiment of the present invention.

FIG. 5 is a sectional view of the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 15 Recording Material (Material to be Heated) 70, 73 Cap (Low Hardness Member) 71 Low Hardness Plate Member 701 Heating Layer (Heating Section) 710 Fixing Film (Rotating Body) 717 Excitation Coil 730 Pressing Roller (Pressing Member) ) 750 side plate n nip part (press contact part) T toner (material to be heated)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroki Kisu 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (5)

[Claims] 1. A rotating body, a pressure member that forms a pressure contact portion with the rotating body, and a heat generating portion that is included in the rotating body itself or that is arranged so as to be in contact with the rotating body. In the image heating device for heating by heating the material to be heated by sandwiching it in the pressure contact portion, the rotor and the side plate lower than the rotor and the side plate holding the rotor in the longitudinal direction are provided. An image heating apparatus comprising a member having hardness. 2. A rotating body, an exciting coil provided inside the rotating body, and a pressure member forming a pressure contact portion with the rotating body, and rotating by generating an eddy current in the rotating body. In an image heating device that heats the body itself, the rotary body and a member having a hardness lower than that of the side plate are provided between a longitudinal end portion of the rotary body and a side plate that holds the rotary body. Image heating device. 3. The image heating apparatus according to claim 1, wherein a cap having a hardness lower than that of the rotor and the side plate is provided at an end portion of the rotor in the longitudinal direction. 4. The image heating apparatus according to claim 1, wherein a plate-shaped member having a hardness lower than that of the rotating body and the side plate is provided on the side plate holding the rotating body. 5. The image heating apparatus according to claim 1, wherein the recording material on which a heat-softening colored powder image is formed and which carries the powder image is formed on the recording material. An image forming apparatus, wherein the powder image is fixed on the recording material as a permanent image to form an image by passing through the recording material.